Railway signaling



April 1 3 E c. SASNETT 1,855,891

' RAILWAY- SIGNALING Filed Dec. 30, 1930 I l l l 5 55 L 551%: I? I 21 54. 19 g 2 m 22 3/75- ll 29 1:: Iii/B 14 15 25 24 Qvm/M F ATTORNEY.

Patented Apr. 26, 1932 PATENT OFFICE EDWARD G. SASNETT, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA RAILWAY SIGNALING Application filed December 30, 1930. Serial No. 505,487.

This invention relates to railway traliic controlling systems, and particularly to automatic train controlling systems of the codecontinuous-indication type. The present application is a continuation in part of my copending application, Serial No. 241,893, filed Dec. 22, 1927, for automatic train control systems, which latter application is a continuation in part of my abandoned application, Serial No. 232,664, filed Nov. 11, 1927, for Railway signaling. The system shown in the present application is a modification, or improvement of the system shown and claimed broadly in my copending application, Serial No. 24,544, filed April 20, 1925.

The present invention provides a system of the above mentioned type in which the track is divided into insulated blocks, each included in a closed track circuit having a battery connected at the exit end of the block and a relay connected at the entrance end, and in which a normally inactive motor device is associated with each track relay and is rendered operative to interrupt the normal track current and cause relatively strong current impulses to flow through the rails of a block when a vehicle enters that block at a time when the block immediately in advance is clear, and in combination with this track system, a vehicle equipment having means to hold a signal and other train controlling devices at clear only while impulses are received from the track. Advantages of the system provided by the present invention are :The system can be applied to any of the existing automatic block systems using continuous current without alteration of the equipment. Heretofore this has not been possible, and furthermore it was necessary to use in connection with such continuous current systems, an expensive high voltage alternating current transmiss on line, which is an exceedingly expensive thing. In the system of the present invention no false clear indication can be caused by failure of insulated oints separating the blocks, which is a highly desirable result, as will be fully appreciated by those skilled in the art. Another advantage is that the code-applying motor devices may be operated only when vehicles enter the respective blocks controlled by said devices, and the current impulses can be made as powerful as desired, rendering it feasible to actuate the translating device on the vehicledirectly by the current impulses in the track rails without the interposition of delicate and troublesome amplifying devices.

The drawing shows diagrammatically one of a large number of diiferent Ways the principles of the invention may be carried out in practice.

The system illustrated comprises a track divided into insulated blocks (only one complete block being shown), along which traf fic is assumed to move in the direction of the arrow. The usual track relays 10 are connected across the track rails at the entrances of the blocks and track batteries 11 are normally connected across the rails at the exit ends of the blocks through back contacts 13 of relays 12. A relay 12 is associated With each track relay, and also associated with each track relay is a quick acting relay 14 and a slow acting relay 15. Normally, relays 12, 14 and 15 are deenergized. The apparatus at only one block station is shown on the drawing, it being understood of course that this apparatus is duplicated at each block station. The track system may of course include the usual track signals controlled by the track relays.

Nhen a vehicle enters the block shown under clear traffic conditions, it causes the circuit of relay 12 associated with the track re lay connected to the block immediately in advance to be closed, said circuit being from battery B, back contact 16 of the track relay connected to the block entered, line wire 17, front contact 18 of the track relay immediately in advance, relay 12, conductor 19 and common wire C. The energization of relay 12 disconnects battery 11 from the track rails of the block entered and closes the circuits of relays 14 and 15. The circuit of relay 14 is from battery B, conductor 20, front contact 21 of relay 12, conductor 22, the winding of relay 14, conductor 23, back contact 24 of relay 14, and back to battery B through conductor 25. The circuit of relay 15 is thesame up to front contact 21, and thence includes conductor 26, the winding of relay 15, conductor 27, back contact 28 of relay 15, and back to battery B through conductors 29 and 25. It will be observed that the circuits of relays 14 and 15 include respectively their own back contacts, so that when the circuits of said relays are closed at front contact 21, the relays will be periodically energized and deenergized, operating their contacts at frequencies dependent upon the electrical constants of the relays.

WVhen relay 15 closes its front contacts 33, battery B is connected across the rails of the block by way of conductors 30, contacts 31 of relay 14, front contact 33 of relay 15, conductors 34, non-inductive resistances 35, and conductors 36. Contacts 31 of relay14'operate to reverse, periodically, battery B with respect to the track rails. Since relay 14 is quick acting and relay 15 is slow acting, it will be understood that while the front contacts 33 of relay 15 are closed, the contacts 31 of relay. 14 will vibrate anumber of times. The frequency of relay 14 can be made high or low as desired.

From the foregoing, it will be understood that when. a vehicle enters a block under clear traiiic conditions, periodic impulses of current-which periodically alternates in direction will flow through the rails and through the wheels and axle of the vehicle, said impulses being separated by a definite time interval which is determined by the electrical constants of relay 15.

One reason for .arranging the apparatus to produce impulses of current periodically alternating in direction is that for a given battery voltage supplied by B, the amplitude of the impulses induced in the train carried receiver described below will be substantially twice as great as would be produced by simply interrupting the current supplied by the battery to the rails.

Any suitable vehicle carried mechanism responsive to the current impulses in the rails may be provided. The drawing indicates a vehicle equipped with .coils 40 carried in advance of the front axle so as to receive the fluxof the current in the track rails. The coils 40 are connected to a relay of any suitable construction, either directly or through an amplifier. The relay shown is of the hot wire type, comprising a fine wire 41 directly connected to coils 40; wire 41 is connected to a contact 42, which is adapted toengage an upper contact 43 when no current flows through wire 41 and to engage a lower .contact 44 when current flows. During the interval between impulses contact 43 is engaged by contact 42, closing the circuit of a slow acting magnet 45, and when an impulse is being received contact 42 engages contact 44, closing the circuit of a slow acting magnet 45. suitable train controlling mechanism indicated diagrammatically at 47, may be provided, and such mechanism is held at ina 'nets will not be ener ized a sufficient time to overcome their electrical inertia, and these magnets will accordingly be unaffected by such impulses. Or if impulses are received separated by an interval substantially greater than that for which the systenris designed,

the magnets will open their front contactsintermittently,. which will place the train controlling mechanism in'danger indicating condition.

It may here be pointed out that the track relays are unresponsive to the current periodically alternating in polarity which is caused to flow in the track rails under clear conditions. If these relays are not inherent ly unresponsive to current of this character they may be made so by suitable inductances inserted in their connections as indicated on the drawing. Thus the system is not dependent for safety upon the integrity of the insulated joints separating the blocks.

I claim:

1. An automatic'train control system comprising in combination, a track divided into blocks, a track relay connected across the rails'at the entrance end of each block, a track battery connected across the rails at the exit end of each block, a quick acting relay and a slow acting relay-associated with each track relay, means for closing the circuitsof said quickand slow acting relays when a train enters the block immediately in rear thereof, the circuits of-said quick and slow acting relays respectively, including back contacts thereof whereby the relays operate intermittently, a source of direct current con nected to the rails ofsaid block under clear traflic conditions through contacts of said quick and slow acting relays in series, said quick acting relay operating to reverse periodically the connections of said source to the rails, and a vehicle having a relay responsive to track current which periodically alternates in polarity but unresponsive to the direct current normally flowing in the rails, and train controlling devices governed by said relay.

2. An automatic train control system operated by continuous current, comprising a track divided into insulated blocks, a track relay connected across the rails at the entrance end of each block, a battery connected across the rails at the exit end of each block, normally inactive means for connecting a source of direct current of higher voltage than that of the track battery periodically to a block with alternating polarity when a train enters that block under clear traific conditions, a vehicle having induction coils carried adjacent the rails so as to receive the flux of the current flowing therein, a relay connected to said coils, and train governing devices controlled by the relay so as to give a clear indication while current periodically alternating in direction is flowing in the rails of the block in which the vehicle is located.

3. An automatic train control system operated by direct current, comprising a track divided into insulated blocks, a track relay connected across the rails at the entrance end of each block, a battery connected across the rails at the exit end of each block, means for disconnecting the battery from a block when a train enters that block under safe traflic conditions and for connecting a source of direct current of higher voltage than that of the track battery intermittently to said block, a timing device controlling the connection of said source of higher voltage so that it will be intermittently connected to the block at fixed time intervals, whereby sep arated groups of impulses will flow through the rails, a vehicle having induction coils carried adjacent the rails so as to receive the flux due to the current flowing therein, a relay connected to said coils, and train governing devices controlled by the relay so as to give a clear indication only so long as the relay is periodically energized.

4. An automatic train control system operated by direct current, comprising a track divided into insulated blocks, a track relay connected across the rails at the entrance end of each block, a battery connected across the rails at the exit end of each block, normally inactive means for connecting a source of direct current of higher voltage than that of the track battery intermittently to a block when a vehicle enters that block under clear traffic conditions, a timing device controlling the connection of said source of higher voltage so that it will be intermittently connected to the block at fixed time intervals whereby separated groups of impulses will flow through the rails, a vehicle having an induction coil carried adjacent the rail so as to receive the flux of the current flowing therein, a relay connected to said coils, and train governing devices controlled by the relay so as to give a clear indication only so long as the relay is periodically energized.

5. An automatic train control system comprising in combination, a track divided into insulated blocks, a track relay connected across the rails at the entrance end of each block, a battery connected across the rails at the exit end of each block, normally inactive means adapted to disconnect a battery from its block and to connect across the rails of said block a source of current periodically alternating in polarity when a vehicle enters said block under clear conditions, said track relays being unresponsive to current periodically alternating in polarity, and governing means on the vehicle responsive to said periodically alternating current flowing in the rails.

In testimony whereof I afiix my signature.

EDWARD C. SASNETT. 

